---
name: "if_urtwn"
section: "4freebsd"
platform: "linux"
package: "freebsd-manpages"
version: "11.0-1"
release: "Debian 9 (Stretch)"
platforms: ["linux"]
url: "https://new.carta.tech/if_urtwn"
---

# if\_urtwn(4freebsd)

Realtek RTL8188CU/RTL8188RU/RTL8188EU/RTL8192CU USB IEEE 802.11b/g/n wireless network device

## NAME

**urtwn** – Realtek RTL8188CU/RTL8188RU/RTL8188EU/RTL8192CU USB IEEE 802.11b/g/n wireless network device

## SYNOPSIS

**options URTWN\_WITHOUT\_UCODE**

To compile this driver into the kernel, place the following lines in your kernel configuration file:

**device ehci** **device uhci** **device ohci** **device usb** **device urtwn** **device wlan**

Alternatively, to load the driver as a module at boot time, place the following line in [loader.conf(5)](/loader.conf/5.md):

```
if_urtwn_load="YES"
```

## DESCRIPTION

The **urtwn** driver supports USB 2.0 wireless network devices based on Realtek RTL8188CUS, RTL8188CE-VAU, RTL8188EUS, RTL8188RU and RTL8192CU chipsets.

The RTL8188CUS and RTL8188EUS are highly integrated 802.11n adapters that combine a MAC, a 1T1R capable baseband and an RF in a single chip. They operate in the 2GHz spectrum only. The RTL8188RU is a high-power variant of the RTL8188CUS. The RTL8188CE-VAU is a PCI Express Mini Card adapter that attaches to the USB interface.

The RTL8192CU is a highly integrated multiple-in, multiple-out (MIMO) 802.11n adapter that combines a MAC, a 2T2R capable baseband and an RF in a single chip. It operates in the 2GHz spectrum only.

All chips have hardware support for  WEP, AES-CCM and TKIP encryption.

The driver supports **station**, **adhoc**, **hostap**, and **monitor** mode operation. Only one virtual interface may be configured at any time.

This driver may use the firmware built with the **urtwnfw** module for some additional features (when URTWN\_WITHOUT\_UCODE kernel option is not set).

## FILES

- */usr/share/doc/legal/realtek.LICENSE*

  **urtwn** firmware license

## HARDWARE

The **urtwn** driver supports Realtek RTL8188CU/RTL8188RU/RTL8188EU/RTL8192CU based USB IEEE 802.11b/g/n wireless network adapters, including:

- Alfa AWUS036NHR v2

  - ASUS USB-N10 NANO

  - Belkin F7D1102 Surf Wireless Micro

  - D-Link DWA-123 rev D1

  - D-Link DWA-125 rev D1

  - D-Link DWA-131

  - Edimax EW-7811Un

  - Elecom WDC-150SU2M

  - Netgear WNA1000M

  - Realtek RTL8192CU

  - Realtek RTL8188CUS

  - TP-LINK TL-WN723N v3

  - TP-LINK TL-WN725N v2

  ## EXAMPLES

Join an existing BSS network (i.e., connect to an access point):

```
ifconfig wlan create wlandev urtwn0 inet 192.168.0.20 \
    netmask 0xffffff00
```

Join a specific BSS network with network name “my\_net”:

```
ifconfig wlan create wlandev urtwn0 ssid my_net up
```

Join a specific BSS network with 64-bit WEP encryption:

```
ifconfig wlan create wlandev urtwn0 ssid my_net \
        wepmode on wepkey 0x1234567890 weptxkey 1 up
```

Create an IBSS network with 128-bit WEP encryption on the channel 4:

```
ifconfig wlan0 create wlandev urtwn0 wlanmode adhoc ssid my_net \
	wepmode on wepkey 0x01020304050607080910111213 weptxkey 1 \
	channel 4
```

Join/create an 802.11b IBSS network with network name “my\_net”:

```
ifconfig wlan0 create wlandev urtwn0 wlanmode adhoc
ifconfig wlan0 inet 192.168.0.22 netmask 0xffffff00 ssid my_net \
	mode 11b
```

Create an 802.11g host-based access point:

```
ifconfig wlan0 create wlandev urtwn0 wlanmode hostap
ifconfig wlan0 inet 192.168.0.10 netmask 0xffffff00 ssid my_ap \
	mode 11g
```

## DIAGNOSTICS

- urtwn%d: error %d, could not read firmware %s

  For some reason, the driver was unable to read the microcode file from the filesystem. The file might be missing or corrupted.

- urtwn%d: device timeout

  A frame dispatched to the hardware for transmission did not complete in time. The driver will reset the hardware. This should not happen.

## SEE ALSO

[intro(4)](/intro/4.md), [netintro(4)](/netintro/4.md), urtwnfw(4), [usb(4)](/usb/4.md), [wlan(4)](/wlan/4.md), [wlan\_amrr(4)](/wlan_amrr/4.md), [wlan\_ccmp(4)](/wlan_ccmp/4.md), [wlan\_tkip(4)](/wlan_tkip/4.md), [wlan\_wep(4)](/wlan_wep/4.md), [ifconfig(8)](/ifconfig/8.md), [wpa\_supplicant(8)](/wpa_supplicant/8.md) *Realtek*, http://www.realtek.com.tw.

## HISTORY

The **urtwn** driver first appeared in OpenBSD 4.9 and FreeBSD 10.0.

## AUTHORS

The **urtwn** driver was written by Damien Bergamini ⟨*damien@openbsd.org*⟩.

## CAVEATS

The **urtwn** driver currently does not support A-MPDU 802.11n transmit aggregation.

For non-RTL8188EUS chips “rate control” algorithm is absent; this may result in increased packet loss in noisy networks.